ONCE AGAIN, a perfidious makeup man has cost the Republican candidate the presidency of the United States.

Just as Richard Nixon was betrayed by the man with the powder puff in the 1960 debates, so was Bobdole skewered Wednesday night in precisely the same manner.

Any competent political analyst knew the instant Bobdole came on camera that what faint hope he cherished of capturing the White House was inevitablely doomed. The poor man was suffering, indisputably, from acute nostril shadow.

If the insidious shadow had been equally dis tributed under both nostrils, the electorate might conclude Bobdole was growing a mustache like Thomas E. Dewey's, and little harm would have been done. Unfortunately, the left-nostril shadow predominated, giving the candidate a seeming sneer, the sneer, unhappily, of a hatchet man.

The importance of nostril shadow in these debates cannot be overemphasized. The records show that in modern times, not a single candidate with nostril shadow has ever won the presidency.

On the other hand, Mr. Clinton's makeup man did him proud. No presidential debater has ever sported a more whitely-powdered nose -- thereby dispelling the image of Bozo the Clown that his opponent has attempted to hang on him.

To be fair to Bobdole's makeup man, however, other factors in this last of these Great Presidential Debates clearly affected the outcome. Perhaps the most important was Mr. Clinton's suit.

It's not generally known, but the President purchases the finest Brioni suits available. He then sends them to Alton Bates, a hedge trimmer in Hope, Arkansas, for tailoring. A genius at his craft, Mr. Bates first alters the shoulders so that the right one hangs half way down to Mr. Clinton's elbow, while the left one creeps close to his neck.

This, coupled with the one shortened sleeve and the overly narrowed necktie, gave Mr. Clinton a look that undeniably captured the hearts of 200 million badly dressed Americans.

Moreover, Mr. Clinton's approach definitely was closer to the studio audience. The sixth or seventh time he stepped from behind the rostrum to build a bridge to the 21st century, he actually came within a record three feet, five inches of a lady who looked increasingly nervous. Instant replays showed the best Bobdole could do was a distant four-foot-two.

True, Bobdole had more jokes than the president -- including a remark that began, "If I were a senior citizen . . ." (I assume that was a joke.) And on eleven occasions, he said how well he was trusted by everyone, if not, perhaps, by his first wife. Mr. Clinton, though, had more statistics. Indeed, his bringing up the San Diego sewage system obviously left his opponent totally nonplussed.

Both men, of course, also strived above all to appear warm and folksy, those being the qualities voters demand most in their presidents. But here, too, Bobdole was betrayed by nostril shadow. Since Attila the Hun, no leader with nostril shadow has ever been called warm and folksy.

So once again the future of our great nation has been determined by the incompetence, if not the treason, of a makeup man. It's what these Great Presidential Debates are all about.